BACKGROUND: Research has demonstrated that variation in availability and utilization of health care resources exist on a range of scales, from regions of the United States, hospital referral regions, ZIP codes, and census tracts. Limited research using spatial analyses has found that variation in medication adherence exists across census tracts. Using spatial analysis, researchers may be able to effectively analyze geographically dispersed data to determine whether factors such as sociodemographics, local shared beliefs and attitudes, barriers to access such as availability of prescribers or pharmacies, or others are associated with variations in medication adherence in a defined geographic area.